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Living Rev. Landscape Res., 5, (2011), 3http://www.livingreviews.org/lrlr-2011-3

Landscape Structure, Landscape Metrics and Biodiversity

Ulrich Walz

Leibniz Institute of Ecological Urban and Regional Development (IOER)Weberplatz 1, D-01217 Dresden, Germany

email: [email protected]

Accepted on 6 October 2011Published on 4 November 2011

Abstract

This paper deals with the question of the role landscape metrics can play in the investiga-tion, evaluation and monitoring of landscape structure, and which linkages between landscapestructure and biodiversity are known. In the first part, the scientific state of the art is pre-sented; in the second part, the meaning of landscape metrics for nature protection, landscapemanagement and biodiversity monitoring is discussed. A number of studies indicate that suchmetrics on an aggregated, overall landscape level are quite appropriate to describe the state ofbiodiversity. On the other hand, gaps in the knowledge become apparent, and the results ofsuch studies are strongly dependent on the scale of investigation and the underlying database.Nevertheless, the landscape structure approach seems to be expedient for management andplanning at the landscape level.

Keywords: landscape mosaic, heterogeneity, landscape functions, biological diversity, land-scape pattern, spatial planning, landscape management, nature conservation

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Living Reviews in Landscape Research is a peer reviewed open access journal published by theLeibniz Centre for Agricultural Landscape Research (ZALF), Eberswalder Strae 84, 15374Muncheberg, Germany. ISSN 1863-7329.

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Landscape Structure, Landscape Metrics and Biodiversity 5

1 Introduction

The structure of a landscape, i.e., its composition and arrangement, and the resulting spatial rela-tionships between its individual elements, can be described and quantified by means of landscapemetrics. This instrument has been used for more than 20 years in Europe and North America ina variety of studies in the scientific and experimental area. They are now finding their way intosuch practical applications as assessment procedures for planning (Botequilha Leitao and Ahern,2002) and monitoring (Wrbka, 2003; Heinz Center, 2008). The present review paper elucidatesthe role that landscape metrics can play, particularly in the collection of the relevant information,and in the evaluation and monitoring of biodiversity. The focus of the paper is laid on landscapemetrics as a means to describe landscape structure and as indicators of biodiversity and the ques-tion of which aspects of biodiversity can be met by landscape metrics. Known fields of applicationin monitoring and landscape management are presented; the impediments encountered, too, are

identified.

2 Definitions

First of all, some explanations of the key words of this article should be given. Landscapestructure means the pattern of a landscape, which is determined by its type of use, but also byits structure, i.e. the size, shape, arrangement and distribution of individual landscape elements.For the delineation of these landscape elements, or so-called patches, often land use or landcover units are used. In this context, land cover refers to the physical surface characteristicsof land (for example, the vegetation found there or the presence of built structures), while landuse describes the economic and social functions of that land. (Haines-Young, 2009, 179). Ofcourse, other spatial elements can also be used, e.g. soil units, habitats or vegetation units from

phytosociology.The heterogeneity of landscapes as a parameter of landscape structure is connoted as

the quality or state of consisting of dissimilar elements, as with mixed habitats or cover typesoccurring on a landscape. It is the opposite of homogeneity, in which elements are the same(Turner et al.,2003,3).

As indices of landscape structure, landscape metricscan be used to describe the compositionand spatial arrangement of a landscape. They can be applied at different levels to describe singlelandscape elements by such features as size, shape, number or for whole landscapes by describingthe arrangement of landscape elements and the diversity of landscape. The reason for using thesemetrics in spatial analysis may be to record the structure of a landscape quantitatively on the basisof area, shape, edge lines, diversity and topology-descriptive mathematical ratios; to document forpurposes of monitoring; or to make the relevant information available as input parameters forlandscape ecological simulation models.

Overviews of the current discussions and the application of landscape metrics are given onthe use of landscape metrics for landscape analysis with Geographic Information Systems (GIS) byLang and Blaschke(2007), the application of landscape metrics in nature protection and landscaperesearch byBlaschke(2000) andUuemaaet al. (2009), on existing landscape metrics and softwarebyMcGarigal et al. (2002) andWalz(2006), and on landscape pattern and landscape indicatorsbyBolliger et al. (2007).

For a definition ofbiodiversity(or biological diversity), the Convention on Biological Diversity(1992) is often cited (United Nations,1993): For the purposes of this Convention . . . Biologicaldiversity means the variability among living organisms from all sources including, inter alia, ter-restrial, marine and other aquatic ecosystems and the ecological complexes of which they arepart: this includes diversity within species, between species and of ecosystems. Biodiversity thuscomprises the fields of genetic diversity, species diversity (number of species in certain units of

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6 Ulrich Walz

space) and diversity of habitats and ecosystems at the landscape level (see Blab et al., 1995, 11,Figure 1). Thereby, each level is dependent on each other. The dynamics of natural processes,such as the changing distribution patterns of species and habitats in space and over time, are alsopart of biological diversity (Blabet al.,1995,11). At each level of biodiversity, three fundamentalcharacteristics of biodiversity can be considered: composition, structure and function (Noss,1990;Waldhardt and Otte,2000). Composition describes the individuality and variety of elements, suchas land use units or species within a region. Structure, by contrast, refers to the arrangement orthe construction of units, the distribution of elements and their relationship to one another. Func-tion, finally, comprises all processes, such as demographic trends, cycles of material or disturbances(Lipp,2009,37). Especially at the landscape level, composition and structure can be described bylandscape metrics.

Figure 1: Levels of biological diversity. Adapted fromBlab et al.(1995).

Biodiversity depends on geo-diversity, i.e., the variety of natural conditions, such as relief, soilcharacteristics and local climate, but in cultural landscapes also on the land use. Geo-diversity,biodiversity and land use diversity as a whole can be called landscape or eco-diversity ( Jedicke,2001, 60). Today, the anthropogenic influence in most regions is very high. A clear distinctionbetween natural and cultural landscapes is virtually impossible. For this reason, it is importantnot only to consider the natural areas or landscape elements, but also the influence of man, for

example, by investigating land use and land use structure.

3 Methods of landscape structure analysis

Use of Geographic Information Systems (GIS) is required to analyse landscape structure usinglandscape metrics. GIS is necessary due to the need to evaluate a large amount of spatial in-formation (such as land use information, habitat types, soil types) and in order to overlay andintersect this information with other information, enabling the parameters of landscape structureto be calculated. In addition, spatial reference units (e.g., natural or administrative units or reg-ular fishnets) are required. Only by overlaying georeferenced spatial data and computing partialcomplex mathematical formulas can landscape structures in large areas be analysed.



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A number of specialised software programmes are now available for calculating landscape met-rics. One of the first programmes to appear on the market was FRAGSTATS (McGarigal andMarks,1995), followed by PatchAnalyst (Rempel,2008) and V-LATE (Tiede).

As the data basis, land use data from official land use surveys or remote sensing data, especiallyfor large areas (e.g., Groom et al., 2006), are often used. One of the main problems in analysinglandscape structure is that the landscape elements need to be delineated and defined, which maybe extremely difficult and arbitrary in some types of landscape. In reality, it is often not easy todelineate a landscape element because sometimes no clear line distinguishes a landscape elementfrom a neighbouring element. Some authors have proposed considering the landscape as gradients(McGarigal and Cushman,2005;Bolliger et al., 2007), e.g., the transition zones between patches.Indeed, in most studies, the delineation of landscape elements is a simplification of reality, whichdepends on data source, scale and, ultimately, the interpreter.

The thematic and geometric resolution influences the results of analyses using landscape metrics

(Baldwin et al., 2004; Castilla et al., 2009; Mas et al., 2010). It is crucial that the scale ofinvestigation (Wiens,1989, 386) and the spatial resolution of the data correspond to one another(Corry,2005,606). Fine-scale or multi-scale methods may be more informative than those basedon only one, or very coarse, scales. For example, in a study by Lawler and Edwards(2002, 242), acoarse resolution of 30 m and higher seemed to be insufficient for statements about bird habitats.The need for multi-scale studies is also illustrated by the fact that studies of habitats often providedifferent results at different scales for the same species (Corry, 2005, 606). The decision whichinformation on land use classes should be included in the landscape structure analysis (thematicresolution) is dependent on the aim of the investigation. The information depth of the data, suchas land use/land cover, should meet the necessary habitat use or habitat types for the investigatedspecies. Sometimes the similarity of types of landscape element is also important for biodiversityat the landscape scale.

Another simplification of reality is that, in most cases of landscape structure analysis, theunderlying relief is not considered. In GIS analyses and calculations of landscape metrics, onlyplanimetric areas and distances are calculated. With extreme reliefs in particular, this can leadto differing results from calculations with real areas and distances (Hoechstetter et al., 2008;Jenness,2004;Blaschkeet al.,2004;Dorner et al.,2002).

These limitations should be borne in mind and viewed with caution when comparing resultsfrom different areas and studies. Care must be taken that the data sources, methods and scales areindeed comparable. The selection of landscape metrics as indicators must also ensure they reflectthe real demands of the species under investigation (Dormannet al.,2004, 70-71).

4 Relations between landscape structure and biodiversity

scientific state of the art

Biological diversity in all its dimensions and facets is always tied to habitats, which need a concreteareal section of the earths surface for their existence. Biological diversity is therefore alwaysdefined for a certain reference area, and landscape structure is a key element for the understandingof species diversity. Spatial heterogeneity, as an expression of landscape structure, indicates thevariability of the systems properties in spatial terms (Kolasa and Rollo, 1991; Li and Reynolds,1995). Therefore it is regarded as essential for the explanation of the occurrence and distributionof species from the local to the global level (Ernoultet al.,2003,240). Against this background, anincreasing number of studies analyse the relationship between landscape structure and biodiversity.The goal is to find variables for modelling the spatio-temporal distribution patterns of species andcommunities (seeBissonette,1997;Dufour et al.,2006;Schindleret al.,2008, 503).



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8 Ulrich Walz

4.1 Landscape structure and diversity of species

It is often mentioned in very general terms that the spatial pattern of the landscape influences manyecologically relevant processes, e.g., the distribution of materials and nutrients or the persistenceand movement of organisms (Turner, 1989, 189). But what connections between the type andstructure of land cover and biodiversity can be found in the literature? An initial overview isgiven in Uuemaa et al. (2009, 811). Numerous studies have shown such relationships to bedeterminants of species diversity (Ricottaet al., 2003, 373). In the following sections, examplesfrom the literature of linkages and variables are given. These are considered important to therelationship between landscape structure and species diversity / patterns of species distribution.

Plants

Important preconditions for high biological diversity are the abiotic site conditionsand the ge-

omorphology. Habitats with spatially heterogeneous abiotic conditions provide a greater varietyof potentially suitable niches for plant species as habitats with homogenous characteristics. Vari-ations in physical structure (e.g., slope direction, soil structure) have proven to be an appropriatefactor for the prediction of the richness, diversity and dominance of plant species (e.g., Hobbs,1988;Lapin and Barnes,1995;Burnettet al.,1998;Nicholset al.,1998;Honnayet al.,2003,241).For example, in studies by Burnett et al. in deciduous forests, the sites with high geomorphologicalheterogeneity were those with the highest plant diversity (Burnettet al., 1998, 367368). There,the variances in plant abundance and diversity were explained best by slope direction and thewater balance. Because of the strong correlation of the abiotic variables and biological diversity,these factors can be used to predict relative levels of biological diversity (Burnettet al.,1998, 368).

By contrast, in a landscape like the Central European cultural landscape, the composition anddiversity of plant species depend on the structure of use affected by people. With respect to

area size,Bastian and Haase(1992, 27) found that the relationship between the number of plantspecies and area size can be described with statistical assurance by means of a logarithmic function.With increasing surface area of shrubs, the proportion of typical forest species in the total numberof species also increased (Bastian and Haase,1992, 27).

The shape of habitatscan affect the number of species, too. For a greater number of envi-ronmental transitions between irregularly shaped habitats, areas can generally include more plantspecies (Honnay et al.,1999,2003, 241242). Therefore, shape complexity can be used to analyseland cover data as an index for species richness (ONeill et al., 1988; Miller et al., 1997), whichimproves the accuracy of the prediction of plant richness. Geometric landscape complexity provedto be a sensitive indicator of plant richness, especially in agricultural landscapes (Moser et al.,2002, 666).

In fragmented landscapes, the distance to viable habitats (isolation) also determines thecomposition and abundance of plant species (Grashof-Bokdam, 1997; Butaye et al., 2001). Lessisolated habitats are generally more species-rich because they can b e easily settled. The con-stant influx of new individuals prevents local extinction due to demographic and environmentalcoincidences (Shaffer,1981;Honnay et al.,2003,241).

An increase in the degree of urbanisation (increase in area proportions and sizes of set-tlements and green spaces, traffic density and shrubs structures) correlates in particular with anincrease in the number of species of neophytes, but also with an increase in archaeophytes andindigenous species. The same is true for the increase in border and seam structures in thelandscape, which create possibilities for settlement (Deutschewitz, 2001, 88). Some species areclosely related to elements of landscape structure, such as edges, roads and certain land use types(Brosofskeet al.,1999,212).

Also, in agricultural landscapes, ecotones, which are linear landscape structures between dif-ferent habitat types, have significant benefits, mainly because they provide habitats after the



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harvest and for hibernation. Ecotones with high structural heterogeneity, such as forest fringesand hedgerows, provide an improvement, too, for regional biodiversity, as they do for the richnessand diversity of beneficial organisms (Duelli,1997, 82).

Natural disturbances along streams, the structure and variety of land use in floodplainsand natural distribution mechanisms are linked to high biodiversity of indigenous species, but alsopromote the establishment and spread of neophytes and archaeophytes (Deutschewitz,2001,88).

These relationships can be made comprehensible by means of landscape metrics. Honnayet al.(2003,248) were able to show that regional plant variety can be predicted satisfyingly on the basisof relatively simple landscape metrics.

Animals

The linkages between wildlife and landscape structure are similar. However, there are differences,

in particular due to the mobility of animals. Thus, species with good ability to spread dependmainly on landscape composition, i.e., the proportion of their preferred habitat type. Landscapestructure is less important for these mobile species (Visser and Wiegand,2004, 59). By contrast,for species with poor dispersal ability, both landscape composition and landscape structure havean arbitrative influence on the frequency of the species. The effect of landscape structure can bereduced to a scale-dependent metric: the average frequency of suitable habitat in a species-specificdistance (Visser and Wiegand,2004,59). Edge effects and distances between patches can influencethe permeability of a landscape. For example, results byRomero(2007) show the dependence ofthe migration behaviour of beetles on landscape structure.

The process of fragmentation of landscapes, in the sense of the piece-meal conversion of aformerly contiguous habitat, usually primarily affects animals with relatively large territories e.g., birds or large mammals. On the other hand, animals with limited mobility are separated

into isolated populations more rapidly by such elements as roads or urban structures (Swensonand Franklin, 2000, 714). However, in science there is no consistent understanding of the termlandscape fragmentation (Jaeger,2002). Today, the term is increasingly used internationally assynonymous for all anthropogenic invasions of landscapes and habitats. By contrast, the Germanconcept ofZerschneidung (lit.: cutting apart), which is usually translated as fragmentation,emphasises the network of linear and areal artificial land use elements, such as roads and settle-ments. This is understood to be an active process which cuts spatial connections and interruptsfunctions. Such land use changes caused by the demand for land for settlement and landscapefragmentation are currently seen as a major cause of the continuing loss of biological diversityworldwide (SRU Sachverstandigenrat fur Umweltfragen, 2005, 52). Several landscape metricsare now used for the measurement of landscape fragmentation through infrastructure ( Walz andSchauer, 2009). The most widespread fragmentation metrics are the number and size of unfrag-mented areas with low traffic (UVR) (Lassen, 1979; Bundesamt fur Naturschutz, 2008) and ofeffective mesh size (meff) (Jaeger,2000).

In many cases, the direct loss of habitats or ecosystems is probably the superior predictor(Strandet al.,2007,147148), even ahead of landscape fragmentation, because habitat size anddiversity play an important part. Certain species prefer more diverse territories (greater numberof patches, smaller size, more edges), as demonstrated byFernandezet al.(2007, 437), e.g., for theIberian lynx or the ocelot (Jackson et al., 2005, 733). For bats, relationships between patch sizeand patch density have been shown in forest areas. Thus, the species richness of bats was highestin partially deforested landscapes (Gorresen and Willig,2004,688). Bees also need specific habitatcombinations that can be described using landscape metrics. This makes it possible to predict thepotential diversity of bees (Baileyet al.,2007, 470).

The shape of patches may play a role, too. It was shown for the ruffed grouse (Bonasaumbellus) that regularly shaped patches are preferred (Fearer and Stauffer,2003,109). Overall, it



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10 Ulrich Walz

is clear that animals can react differently to habitat diversity. Different scales have to be taken intoaccount. The identification of such scales remains a key objective in landscape ecology (Turner,2005, 329).

Ecotones or edges, as transition zones, are often particularly rich in species. In studies ofedge biotopes in the agricultural landscape of Saxony-Anhalt, species numbers were almost twiceas high as those within the fields. The species composition and dominance of edge biotopes werevery different from those in the fields. Introducing edge habitats to forests can also affect thefauna. In such cases, species richness may temporarily increase due to migration of specific edgespecies, but only at the expense of species of the forest interior. Therefore, birds can be useful asan ecological indicator (Noss,1983, 702).

The environment of the habitats, i.e., the context and surrounding landscape matrix,plays an important part. For the management of grassland birds, for example, it is important toinclude quantity and context of the embedded habitats, i.e., the surrounding matrix as well as food

resources (Hameret al.,2006,581).The degree of disturbance by landscape change and other factors of human influences in

the surroundings have a significant impact on species richness. Thus, for the correlation of birdscommunities with road density and forest area, the distance to the nearest built-up area, thedensity of human settlement, and the degree of imperviousness were found to be significant factors(Sundell-Turner and Rodewald,2008,223).

Geomorphological diversityalso emerged as a significant impact for the fauna. Due to themobility of animals, however, it appears to be less limiting than it is to plants. However, manyanimal species depend on certain plant species (Burnettet al.,1998,368).

Habitat modelling

Landscape metrics are also used for habitat modelling of individual species or species groups, e.g.,

by Dormann et al. (2004); Fauth et al. (2000); Fernandez et al. (2007); or Grillmayer (2000).For example, Steiner and Kohler (2002) were able to show the existence of a clear dependenceof the species diversity on landscape structure in model experiments. With a decreasing degreeof landscape heterogeneity in the model, both local and regional species diversity also decreased.The importance of considering space, habitat structure and landscape patterns is illustrated byDormannet al. (2004,7071).

Results on linkages between landscape structure and species

In the literature analysed, the following properties of landscape patterns that have a positive effecton biodiversity were mentioned:

a high proportion of semi-natural biotope types;

large areas;

high biotope diversity;

high structural diversity;

high connectivity;

high geomorphological diversity.

However, some of these properties are mutually exclusive (for example, high structural diversityand large surface area of individual patches) (Zebisch,2004,27). In addition, properties that arebeneficial for a single species can be definitely disadvantageous for another. Depending on the



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specific characteristics of the organisms, and depending on the spatial scale, the effect of landscapestructure on the viability of the organisms can vary greatly ( Visser and Wiegand,2004, 62). Noclear assignment to a quality (e.g., high structural diversity is desirable) is possible (Zebisch,2004,27).

Furthermore, land use in and of itself may be not sufficient to predict species richness anddistribution. In studies byCardilloet al. (1999,432433), it explained less than half of the speciesrichness and occurrence. Therefore, a set of variables should be used, which includes the landuse in conjunction with such other landscape characteristics as habitat structure, composition ofvegetation and soil characteristics. However, particularly in cultural landscapes, the influence ofland use on patterns of species distribution could be greater than the influence of the original andnatural landscape parameters. For investigations at the regional level, land use can be crucial forspecies composition and richness (Deutschewitz,2001,78).

All in all, Duelli (1997, 88) and many other authors (e.g., Bailey et al., 2007; Ortega et al.,

2004) hold that the evaluation of patterns of the landscape mosaic can serve as a substitute forthe recording of regional biological diversity, as a form of knowledge-based assessment. In general,broad environmental diversity leads to high species diversity (Ricotta et al., 2003, 373). Size,surface area and spatial relationships between patches thereby play an important role ( Daleet al.,2000,639). In accordance with the mosaic concept, regional biodiversity depends mainly on suchstructural parameters as habitat diversity or landscape heterogeneity, and the dynamics of meta-communities (Duelli,1997,81). As relevant measures, he mentions the diversity and heterogeneityof habitats, and the portions of natural and semi-natural habitats (see Table 2). Thereby it isassumed that such areas rather have a great diversity of habitats due to their size and thereforealso greater biological diversity (Dramstadet al., 1996; Botequilha Leitao et al., 2006, 11). AlsoHonnay et al. (2003,248) come to the conclusion that landscape metrics appear to be suitable topredict biotic processes. Therefore, according toDuelli(1997), the assessment of biodiversity at a

higher, integrated level can be based on landscape parameters.

4.2 Landscape metrics for monitoring biodiversity

Since the complexity of biological diversity is difficult to describe, most ecologists have takenthe practical way to research and to identify the biological diversity at the species level (Feestet al.,2010, 1078). Therefore, the selection of structural indicators was undertaken specific to thehabitat type or tested species studied. Local data on species diversity can provide informationas a proxy for regional biodiversity. An investigation of flora and fauna is, however, typicallynot comprehensive, but rather generally covers only a small proportion of all species. The cleardetermination of the diversity of various taxonomic groups requires very high efforts, knowledgeand money. Hence a good substitute is needed. By combination of indicator species and groupswith spatial environmental data (Heino,2010,112) and landscape structure, the power and deputyinformation can be increased and expanded geographically (Faith et al.,2003,317).

Which parameters are suitable for the characterisation and description of landscape diversity,and can therefore be used as an indicator for biodiversity? In principle, a few indicators aresufficient to ascertain landscape patterns (Riitters et al., 1995; Cain et al., 1997; Lausch andHerzog,2002, 13). However, biodiversity cannot be described only by a simple number, as thereare various qualities of spatial patterns (Tischendorf,2001;McAlpine and Eyre,2002;Neel et al.,2004). A selection of indices representing various aspects of biodiversity is much more informativeand capable of interpretation (Feestet al.,2010,1080). However, the use of many highly correlatedindices provides no new information, and leads to problems in interpreting the results (Joneset al.,2001;Li and Wu,2004). For this reason, mutually independent indices should be selected (Schindleret al.,2008,503).

By means of indicators in monitoring, dramatic changes in values can be detected and serve



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12 Ulrich Walz

as an early warning, and as an indication of the necessity for deeper investigation, even if nospecific limit values can be defined (Bocket al.,2005,336). Landscape metrics may also be used toidentify hot spots of biodiversity in rural Europe. Although they do not replace direct measurementof species biodiversity, these surveys can help make them more effective and less costly (Baileyet al., 2007, 472). Often mentioned as possible parameters are distribution, abundance and areaproportions of land use types (e.g., Schupbach et al., 1999, 212). Other aspects are the richness(number of land use types) and the uniformity of the landscape (Nagendra,2002,178).

Indicator systems

Due to the importance of landscape structure for biodiversity, there are currently a number ofactivities to develop indicators for monitoring biodiversity at the level of ecosystems or landscapes(EEA, 2007, 2005; BMU,2007). Ideally, the same biodiversity indicators should be used at the

global, national, regional and local level. However, this is not possible for practical reasons. Thespecific requirements for monitoring and for financial resources vary from country to country.Many monitoring systems have their own historical developments and even the methods for thesame indicator differ from place to place (Strandet al.,2007,17).

In Germany there are a number of indicator systems for monitoring land use change andbiodiversity (see also Table1):

Indicators of Sustainable Development in Germany (Federal Government,2002;Federal Sta-tistical Office,2010).

The Core Environmental Indicator System of the German Federal Environmental Agency(Umweltbundesamt,2007).

Sustainable development indicators of the federal and state governments (LIKI indicators)(LIKI,2011).

Indicators of the national strategy on biological diversity (BMU,2007).

However, there is still no complete and interoperable, nationwide monitoring system for biodi-versity at the federal level. An earlier approach that could have served that purpose was so-calledecological area sampling(okologische Flachenstichprobe) (Droschmeister,2001), whereby indica-tors of cultural influence and intensity of use, rarity or threat of habitats, and structural diversitywere to be surveyed at the landscape and habitat levels in defined test areas (Hoffmann-Krollet al., 1995, 595, see also Table 2). Complementarily, the Shannon Diversity and Evenness andthe Fractal Dimension were proposed (Back et al.,1996, 2133). Unfortunately, this concept wasnever fully implemented nationwide.

Stachow (1995) has proposed a system of indicators for monitoring agricultural landscapechange. As a complex of factors important for the formation of communities, he mentions thenatural conditions of the site (terrain, climate and soil type) and the type and intensity of humanimpact. The indicator system, therefore, is composed of three landscape indicators: the physicalor natural diversity of landscapes, the diversity of land use, and the naturalness of land use. Hestarts from the assumption that increasing naturally the animation of the terrain is associated withan increase in various site conditions. Based on the criteria length of contour lines in m/ha percommunity, height difference between the highest and lowest contour lines in the community,and river length and area of surface waters, he arrives at statements regarding natural spatialdiversity (Bork et al., 1995, 290). The variety of land use is identified based on the diversity ofmajor land use types, length of forest fringes, field sizes and variety of crops within agriculturalareas. The degree of naturalness is derived from natural conditions of sites, and the situationregarding crops (Borket al.,1995, 292293).



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Table 1: Selected indicators reliable to biodiversity and land use change in Germany and their use in the

different indicator systems

Indicator set / Institu-tion

Sustainabledevelop-ment in

Germany

Core envi-ronmentalindicators

Indicatorsof the

Germanstates

Nationalstrategy onbiodiversity

Dissection of the landscape(Landscape fragmentation)

x x x

Urban sprawl x x

Natura 2000 area designa-

tions

x x x

Size of strictly protectedareas

x x x

Land use: Increase in landused for housing and trans-port

x x x x

Recreation areas x

Species diversity and land-scape quality

x x x x

A number of authors have emphasized the importance oflandscape diversityas an indicator ofspecies diversity in monitoring agricultural landscapes. In addition to land use practices, especiallyhabitat heterogeneity plays an important part. It has often been noted that even using a fewlandscape and land use parameters, inferences can be made regarding large-scale patterns of speciesdiversity (Benton et al.,2003;Tewset al.,2004;Billeter et al.,2008,141142).

In Germany, the avifauna is used as a nation-wide indicator of biological diversityat the specieslevel (BMU,2007;Sukopp,2007). This indicator is contained both in the national set of sustainabil-ity indicators (Federal Government,2002) and in the set of indicators for the national biodiversitystrategy. For the calculation of the indicator, trends in the stocks of 59 selected bird species arerecorded, representing the most important landscape and habitat types and land uses in Germany(agricultural land, forests, settlements, inland waters, coasts and seas, and the Alps). The sizeof the stocks should directly reflect the suitability of the landscape as a habitat for selected birdspecies. However, the condition of the landscape (structure and intensity of uses) is not registered.

In the case oflandscape fragmentation by infrastructure, nationwide regular monitoring takesplace. The German Federal Agency for Nature Conservation (BfN) regularly determines unfrag-mented open spaces equal to or larger than 100 sq. km. Also, effective mesh size meff (seeabove) has in recent years been applied in several German states, including Baden-Wurttembergand Hesse, and is now established as a core indicator in the environmental system of indicators(LIKI,2011).

At the European level, the European Environment Agency already in 2000 submitted a reporton Landscape Diversity in the EU (EEA,2000), in which landscape indicators for fragmentation,diversity or heterogeneity, and spatial arrangement and organisation of landscapes were used.The landscape metrics applied were: Patch Density (PD), Edge Density (ED), Perimeter/Area



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14 Ulrich Walz

Table 2: Indicators of quality of landscape structure in the framework of spatial ecological sampling(Dieren and Hoffmann-Kroll,2004,291293).

Superordinateissue

Special issue Indicator

Use intensity

Naturalness / hemeroby Surface areas of natural and semi-natural habitat types [in %]

Degree of sealing Proportion of sealed surface [in %]

Erosion risk caused by water, de-pletion of arable soil

Proportional area of arable land,viticulture and intensive woodyplants with slope >9%

Fragmentation and isolation ofhabitats

Total length of all roads (5 mwide) outside of settlements [inm/sq. km]

Structural diversity

Habitat diversity / diversity ofliving conditions

Number of non-technical habitattypes per sq. km

Monotony of living conditions Average size of parcel of arable

land and vineyards [in ha]

Density of linear refuges andwildlife dispersion axis

Length of linear elements/ edgestructures (hedges, forest belts,tree rows, avenues, seams) persq. km

Density of small habitats asrefuges and dispersal centres forwild species

Number of small habitats (


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Ratio (PAR), Number of Classes (NC), Shannons Diversity Index (SHDI), the Interspersion andJuxtaposition Index (IJI), and the Land Cover Diversity Index (LCDI).

As part of the EU project SPIN (Spatial Indicators for European Nature Conservation) (Bocket al.,2005), the potential of landscape metrics for pan-European nature conservation was explored,especially for the Natura 2000 network. Thereby, landscape metrics were applied, e.g., for thedetermination of the size of the ecologically effective protected areas. For this purpose, indicessuch as TCA/TCCA (total core area and total class core area), NCA (number of core areas) andCAI use (core area index) were used.

In a joint project forCultural Landscape Research in Austria, landscape metrics were calculatednationwide (Wrbka,2003). They have been used, for example, in the fields of landscape composi-tion, habitat area, landscape configuration, ecological functions, habitat fragmentation, diversityand anthropogenic influence. For biodiversity monitoring in South Tyrol, five indicators were se-lected by experts to measure both heterogeneity of landscape structure and human impact (Tasser

et al., 2008, 208). These include an index of landscape diversity (EEA,2000), effective mesh size(Moseret al.,2007), hemeroby (Steinhardtet al.,1999), naturalness of near-river areas (adaptedfromXiang, 1996) and agricultural intensity (UNEP, 2001). Tasser et al. (2008, 208) expandedthis set by two indicators of species diversity: the area-weighted richness of vascular plants, andthe frequency-weighted absolute species richness of vascular plants.

In the United States, the Heinz Center developed landscape indicators, of which eight refer tothe landscape structure (Heinz Center,2008). They are to be used to identify large-scale landscapepatterns and human-induced landscape changes at the national level.

Metrics for monitoring

The monitoring of biodiversity is carried out almost solely at the level of species diversity, primarilyon the basis of species richness, mostly using surrogate species or groups (especially birds andvascular plants). In the last few years, however, doubts as to the suitability of species or speciesgroups for the estimation of biodiversity have increased. The criticism has concerned, in particular,conclusions drawn from the recording of species regarding the diversity of organisms of other taxa,or at other scales (spatial requirements etc.).

As a result, the focus has been directed towards the importance of landscape diversity for theexpression of biological diversity. Increasingly, approaches and indicators for this level of biodiver-sity are being developed, especially for landscape diversity in agricultural and rural landscapes. Itshould be noted, however, that despite the presence of previous approaches, indicators of landscapeand environmental diversity are not included in the indicator system of the United Nations, or inthe German National Biodiversity Strategy. Here, there is a clear need to catch up.

Reference is often made to the potentials of remote sensing for cost-effective collection and

presentation of landscape diversity. In particular, due to sophisticated sensor technology andresolution, as well as better availability of data, remote sensing, in combination with climate andenvironmental data, could lead to a more precise characterisation of landscape diversity, and thusa better assessment of species diversity.

Several examples from the great variety of landscape metrics found in the literature analysedhave been compiled; these are repeatedly mentioned, or stand out as particularly significant (Ta-ble3).

It is obvious that landscape metrics must always be selected for different tasks or problems,and in accordance with the available resources. A single index, or always the same set of indices,is not automatically appropriate for all study ob jects. Similarly, because of their complexity, acombination of indices should generally be preferred to individual indices for the estimation ofbiodiversity.



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16 Ulrich Walz

Table 3: Important landscape metrics in the field of biodiversity

Function Index Source

Prediction and assessmentof biodiversity in landscapemosaics of the agriculturallandscape

(1) habitat diversity (number of habitat typesper unit area)(2) habitat heterogeneity (number of habitatpatches, lengths of ecotones per landscape unit)(3) portions of natural, semi-natural and inten-sive land used

(Duelli, 1997,88)

Prediction of biodiversity Surface area of semi-natural ecosystemsPatch distribution, edge and patch density

(Dramstad et al., 1996;Bote-quilha Leitao et al., 2006,11)(Bailey et al., 2007,466467)

Prediction of species diver-sity

Patch Density PD, Largest Patch Index LPI,Simpsons Diversity Index SIDI, ProximityPROXMN, Patch Richness PR, Edge density

ED, Euclidean Nearest Neighbour ENNCV, Cir-cumscribing Circle: CIRCMNNumber of species, population sizes, number ofviable populations and habitat areaLandscape diversity, intensity of agriculturaluse, frequency weighted absolute species rich-ness of vascular plants

(Bailey et al., 2007,466467)(Strand et al.,2007, 121)(Tasser et al., 2008,219)

Planning of biotope net-works

Proximity Index (allows assessment of individ-ual patches depending on functional connectionwith surrounding habitats)Density of landscape elements, indices of con-nectivity/ isolation

(Kiel and Albrecht,2004,331)(Baguette and Van Dyck,2007,11251126)

Assessment of protectedareas, habitat requirementsof species of the core areasand edges

Total Core Area TCA,Total Class Core Area TCCA,Number of Core Areas NCA,Core Area Index CAI,Cority

(Bock et al., 2005)

Landscape fragmentation Effective mesh sizeArea of unfragmented open spaces

(Jaeger,2000)(Lassen,1979;Bundesamt furNaturschutz,2008)

Quantification of the floris-tic diversity (habitat func-tion)

Shannon Diversity SHDI,Number of different classes and their distribu-tion

(Herbst et al., 2007)

Smallness, shape richness aswell as structuredness of alandscape (natural spatialdiversity)

Edge density ED,Density of patch boundaries or linear elementsin a landscapeLength of contour lines per area, elevation dif-ference between highest and lowest point, riverlength and area of surface waters

(Herbst et al., 2007)(Stachow,1995)

Diversity of land use Diversity of main land use types, length of for-est edges, field sizes

(Stachow,1995)

Floristic species richness(general)

Distance (isolation) to usable habitat, largestpatch index LPI, patch size coefficient of varia-tion PSCV

(Grashof-Bokdam,1997;Butayeet al., 2001)(Banko et al., 2000,28)

Floristic species richness(in natural ecosystems)

Topographic and edaphic variables, in particularslope direction and water balanceShape complexity of the habitats

(Burnett et al., 1998,368)(Honnay et al., 2003, 241242)

Floristic species richness(in landscapes)

Surface area of land use,Geometric landscape complexity, Number ofShape Characterizing Points NSCPLength of edges

(Bastian and Haase,1992,27)(Moser et al., 2002,666)(Bastian and Haase,1992,27)

Faunal species richness Road density, forested area, distance to nearestbuilt-up area, density of human settlements,degree of soil imperviousness

(Sundell-Turner and Rodewald,2008,223)



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Limitations

Buchs et al. (2003) summarise limitations which occur in relation to the use of indicators for bio-diversity monitoring. First, it must be noted that there is no indicator for biodiversity as a whole.Every aspect of biodiversity also requires its own indicator with very specific and well-definedcharacteristics, with agreed-upon definitions for their use (Tasser et al.,2008, 205). Furthermore,the classification of land use and habitat type mapping must be considered precisely. Default typ-ifications may not necessarily be suitable for a specific question. Often, visually delimitable unitsare equated with functional structures and habitats (Filipet al.,2008,534535).

The indices used must also be questioned. In particular, the Shannon Index is used almost as astandard for large-scale landscape analysis (Filipet al.,2008, 536). However, it does not reflectthe spatial distribution of classes, although this is crucial for the diversity of a landscape. Thus, itis irrelevant to the result value of the index whether the landscape elements present a large area or

a mosaic, even though this factor should be crucial for the diversity of a landscape. ( Filip et al.,2008, 536). Moreover, even at the species level, the Shannon or the Simpson index is generallyconsidered as not useful for large-scale monitoring of the integrity of biological diversity ( Lambet al., 2009, 439). Another problem, not only in the field of biodiversity, is that the selection ofindicators is often driven by the availability of information. However, with respect to biodiversity,this can lead to delusive or adverse results (Failing and Gregory,2003,129).

A review of the literature makes it clear that a wide variety of indicators and systems is nowavailable which are usually hardly comparable to one another. Especially in the field of sectoralindicators, a large number of other systems can be expected, which and this seems to be anunderlying trend have been developed and used relatively independently of one another (Mullerand Wiggering,2004,122).

5 Conservation and management issues landscape metricsfor spatial planning and nature protection

As shown above, the type of land use and the pattern of the landscape, the matrix, and also thearrangement of individual patches and their relative positions are crucial for the conservation ofbiological diversity. Land use changes in future will have one of the biggest effects on biodiversity,beside climate change (Salaet al.,2000). The management of land use patterns is therefore of greatimportance. Even in 1979, Haber wrote: Spatial diversity should be accorded great importance inthe planning process, as it identified the arrangement or mosaic (pattern) of different, but similarspatial units or cells in a landscape (-diversity) (Haber,1979, 21). As an overarching approachto planning, Forman (1995, 139) and others (Forman and Godron, 1986; Franklin and Forman,1987;Turner,1989) have suggested a so-called aggregate-with-outliers model. This means thatareas used by humans should be aggregated as closely as possible, while small natural patches andcorridors through developed areas are preserved. At the borders of the remaining large naturalareas in the surroundings, human-used areas should be arranged as ever smaller and more distantislands. In their opinion, this model increases genetic diversity, provides a distribution of risk ofstrong interferences, and has other environmental benefits (Forman, 1995, 139140). However,in already highly developed regions of the world, where nearly every place is subject to humanuse, such a model is hardly suitable. Therefore,Haber(2008,95) proposes a land use pattern asslender and diverse as possible. In his opinion, this is the only promising approach for maintainingbiodiversity, since land use change along with climate change, with which it interacts will havethe greatest future impact on biodiversity (Haber, 2008, 95). Hence, he argues, it is necessaryto reverse the homogenisation of land use, at least partially (Haber, 2003, 37). The goal of hisconcept of differentiated land use is to implement the objectives of nature and landscape



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18 Ulrich Walz

conservation area-wide(Haber,1989,21). It provides that:

1. environmentally harmful, intensive land use not take 100% of the surface within a spatialunit, but should keep sufficient space available for relieving or buffering uses (10 15%);

2. to avoid large, uniform surfaces, the prevailing land use be diversified in itself; this shouldapply both to agricultural land and to urban areas;

3. in an intensively used unit, at least 10% of the area be kept in, or developed to a nature-emphasized state, as is possible with netlike distribution.

The issues raised under 1 and 3 could be partially identical, or overlap, but there are differentobjectives (Haber, 1998, 60). Other authors have adopted this concept, e.g., Buchwald (1982,Figure2). He assigned protection categories to different landscape elements.

Natural or semi -natural

ecosystems

Agricultural and forestal

ecosystems with extensive use

and small-scale land use structure


ecosystems with extensive use

and adequate structural diversity


ecosystems only for production

National parks

Landscape

protection areas

Production areaNatural

monument

Linear habitat

Small-scale

structure

Nature

protection areas

1 2 3 4

Figure 2: Differentiated agricultural land use. Adapted from Buchwald (1982, 103). In category 3,measures for structural enrichment are necessary.

This approach is also supported by the concept of a tiered target system of natureprotection at 100% of the area (Plachter, 1991). There, Erz (1980) distinguishes four stagesof the influence of nature conservation, ranging from strict nature reserves to extensively usedareas and land which could be opened for additional intensive land use. On the latter, however,a minimum diversity of habitat conservation should be preserved by accompanying measures, orrestored.

All these concepts emphasise the need to integrate the entire area of the landscape into theeffort to maintain biodiversity. In this sense, dynamic conservation and development strategiesfor the cultural landscape must be found. More attention should be paid to ecosystem-specificdevelopment processes (succession) and spatial-functional aspects, as they play a key role, par-ticularly for animals. Nevertheless, the designation of protected areas is evidently still necessary.They are included in the above concepts as a system of core areas for the protection of hard-to-renew ecosystems, i.e., those with long development periods, and to preserve severely threatenedelements of nature. But it is absolutely necessary to include the surrounding landscape. This



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means that there is not only a need for a large-scale ecological network (see below) outside ofthe core areas, but also for the preservation of a minimum share of small-scale structures. Forexample, in agricultural areas, field edge structures are particularly important as habitats for thepreservation of biodiversity, both between the fields towards neighbouring areas with other landuse types (Hietala-Koivuet al.,2004, 75). A minimum of border structures amounting to at least1 2% of the total agricultural land area can be justified on the basis of the data in the literature.(Knickel et al., 2001,46). Also, the German Federal Nature Conservation Act (BNatschG,2009)stipulates a minimum percentage of such elements (5 (2) and 20 (6)). One example is providedby the landscape framework plan in Mecklenburg-Western Pomerania, where regional minimumdensities of landscape elements are defined (Muller et al., 2008). Using a GIS based on availabledigital data, regional densities of structures were determined and objectives for regional minimumdensities per spatial unit were quantified. For approximately one third of the municipalities, anurgent need for the enrichment of landscape elements was ascertained.

Conservation of nature

What do the findings from these various studies mean for nature conservation? First, it is clear thatthe landscape level requires much more attention. Understanding the importance of the landscapematrix is important for the conservation of biological diversity. A variety of studies have shown thatthe protection of the widest possible diversity at the landscape level and a corresponding control ofthe development of the landscape matrix is more effective than the protection of individual speciesand habitats (Franklin, 1993). At the species level, however, it is difficult to develop generalconservation strategies while managing a variety of species, as different demands on the vegetationor on landscape features and territorial claims often lead to conflicting objectives ( Rey Benayas andde la Montana,2003,365; Howell et al., 2000, 559). Against this background, there is a growing

consensus that the landscape level is the most important level for the management of biodiversity.Conservation strategies must therefore be implemented at this scale to be successful (With,2005,240).

In a system of graded protection intensities of the entire landscape, protected areas certifiedas core areas are still important, but these should be designed to be significantly larger thanis currently the case. So far, only a few reach the threshold of effective habitat size (Wiersmaet al.,2004,783;Schmitt,2004,94;Kaule and Henle,1991,17). Particularly in relation to possiblechanges that may result from climate change, the goal of protected areas should be to maintain ashigh as possible a level of ecosystem diversity, with a maximum of ecological gradients, and thusmaximum biodiversity(Swenson and Franklin,2000,714;Juutinen et al.,2008,37503751). Theeffectiveness of protected areas for the conservation of biological diversity is, however, affected notonly by size but also, and essentially, by the landscape matrix of interdependent connectivity, andby human activity in the surrounding area (Franklin,1993, 202;Wiersma et al.,2004,773;With,2005,240). Therefore, for the designation and management of protected areas, such factors at thelandscape level as land use types and intensities, or landscape and habitat change in relation tothe population density in and around the protected area, should be considered. In the surroundinglandscape matrix, small and medium-sized areas located close together are needed (Franklin,1993,203). This it is not achievable only with protected areas, but must be considered in the contextof the management of traditional agricultural and forestry systems outside of protected areas(Rey Benayas and de la Montana,2003, 366).

Opinions differ somewhat with respect to the importance of protecting natural spatial diversity.Although it is often argued that the protection of geomorphological heterogeneity could be anefficient strategy for the preservation of existing and potential biodiversity, it has been shown thatthis factor is closely linked to biodiversity in discontinuous landscapes (Nicholset al.,1998,378).Especially in relation to long-term environmental change (e.g. climate change), landscapes with



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20 Ulrich Walz

high geomorphological heterogeneity are considered important, since they have the potential foraccommodating many plant communities, despite changing species composition (Burnett et al.,1998, 369). However, other voices warn against limiting efforts in protection of biodiversity only toachieving maximum possible landscape heterogeneity, as this would neglect the needs of specialisedor endangered species. The high diversity of species in a heterogeneous landscape, it is argued,largely reflects the large number of generalists, which is then promoted by diversity-enhancingmeasures (Atauri and de Lucio,2001, 157).

The different goals of protection of biodiversity can lead to conflicts with very real policy im-plications. Examples are the maintenance of ecological services, consideration of ethical principles,protection of single target species (e.g., charismatic large animals), the avoidance of aestheticloss, or the protection and improvement of social and economic values. To address these problems,the goals must be described in detail, and matching indicators defined (Failing and Gregory,2003,123). For this purpose, specific landscape metrics can be applied to define minimum equipment

numbers of the landscape. Examples include the Nature Protection Act in Germany (BNatschG,2009) and state laws which demand the determination of structural minimum densities of land-scape elements (see above), or, related to this, restrictions on the use of agricultural pesticides ifminimum standards are not achieved (Enzian and Gutsche,2004).

Biotope networks

One of the points of departure for the design of ecological networks is the assumption that theconnection between landscape elements for the conservation of biological diversity can be at least asimportant as their size. Landscape structures that support the connectivity of species, biologicalcommunities and ecological processes are therefore a key element of conservation in a human-altered environment (Bennett,2003,8). The importance of wild animal migration corridors for the

protection and management of biodiversity is widely known (Hargroveet al.,2005,361). Landscapeelements in the open countryside can contribute effectively to the conservation of biodiversityas habitat islands if they are interconnected by corridors (Ahern, 1991, 139). For example, itwas pointed out that connecting elements such as forest corridors or small forest patches servingas stepping stones can reinforce the distribution of species in the forest interior. The spreadbetween the individual elements (patches) is crucial for the prevention of genetic stagnation insmall populations (Noss,1983,703704).

Again, however, the entire landscape matrix plays a significant role. Efforts to improve theconnectivity of fragmented landscapes often focus on the remnants of natural and semi-naturalhabitats, and the distribution of stepping stones and corridors. However, it would often be morepractical, and perhaps more effective, to reduce the virtual isolation of fragments by changingmanagement practices in the surrounding matrix, e.g., by laying out corridor or stepping stonehabitats (Ricketts, 2001, 97). Such networking is not necessary for all types, or in every case.Self-pollinating plant species have done without genetic exchange for eons. Studies by Ockingerand Smith(2008, 27) on the spread of insects also show that corridors do not necessarily have apositive effect, but that the quality of the surrounding matrix plays an important role. Even highlypropagating species are relatively independent of such networking elements, as shown above.

Landscape metrics have been used to design ecological networks for quite some time. For exam-ple, indicators such as the density of landscapes elements, or metrics on connectivity or isolation,need to be stated for the configuration of landscapes. Baguette and Van Dyck (2007,11251126)show that even simple measures can be beneficial landscape tools for the assessment of landscapeconnectivity. Nevertheless, they advocate cautious use in generalisation of the relationship betweenlandscapes and species (Baguette and Van Dyck,2007,11251126). Kiel and Albrecht(2004,331)recommend especially the proximity index for habitat network design, as it allows an assessmentof individual areas in terms of functional integration with the living spaces of the surroundings.



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Metrics in planning and nature protection

The successful protection of biodiversity requires the preservation of adequate habitats and ecosys-tem functioning in the context of the entire landscape complex at various spatial and temporalscales. Particularly in light of future land use changes which will increase further and expectedclimate change, landscapes with high geomorphological heterogeneity are considered important.Therefore, in planning and nature conservation, the landscape level needs much more attentionthan has been the case to date. An understanding of the importance of the landscape matrix andan appropriate management are important for maintaining diversity.

Protected areas should still be included in the strategy; however, they should be designated asmuch larger areas than before. Above all, more emphasis should be placed on their contributionto ecosystem diversity and thus a maximum of possible (potential) species diversity. The selectionof protected areas, therefore, must not only focus on endangered species.

Outside of protected areas, the management of traditional agricultural and forestry systemsremains a key element of nature conservation. The consideration of the entire landscape matrixshould also include the preservation or development of a functioning mosaic of interconnectedhabitats as an ecological network associated with areas of intermediate intensity cultivation (agri-culture, settlement, etc.), with a minimum number or density of small-scale, semi-natural landscapeelements.

In this area, landscape metrics can help improve the theoretical foundation of the methodsof landscape planning and their practical application, with the goal of sustainability (Botequi-lha Leitao and Ahern,2002,65). Examples of the use of landscape metrics in spatial planning canbe found in landscape planning, in the design of ecological networks and in nature conservation.Landscape metrics can thus be used for the selection of protected areas (Sundell-Turner and Rode-wald,2008;Harrison and Fahrig,1995), the evaluation of the landscape (Botequilha Leitao et al.,2006;Herbst,2007), or the analysis of equipment deficiencies of the landscape (Mulleret al.,2008)

(see below). For example, Herbst et al. (2007, 236) examined landscape metrics for usefulnessas an assessment tool in strategic landscape planning. In the range of species and communities,particularly the measures Shannon-Diversity and Edge Density were found to be useful.

6 Conclusions

Due to increasing demand and intensification of land use by humans, land use changes are expectedto be the most significant driver of change in biological diversity in future (Salaet al.,2000,1772).Against this background, it seems all the more important to explore the relationships between landuse structure and biological diversity, and to understand the consequences of different landscapepatterns for the composition and diversity of plant and animal species. On this basis, alternativesfor the design of the landscape can and must be developed ( Brosofskeet al.,1999, 214).

In the context of biodiversity, landscape metrics can be used to assess landscape patterns, todefine the minimum equipment, to carry out isolation or connectivity analysis and to recogniseand monitor the results in changing landscapes. Moreover, landscape metrics have come to playa considerable role in the analysis and assessment of biodiversity, especially in local studies ofspecies distribution and modelling, analysing and characterising the diversity of landscapes (aspart of biodiversity), and for monitoring. It can be stated that:

Landscape metrics are applied in a variety of local studies and research projects. Only afew indices are used constantly in different studies. Thus, there is a lack of comparability ofstudies and problems in the formation of general statements.

Landscape metrics are already used in monitoring, but there is no standard set of landscapemetrics which is frequently used.



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22 Ulrich Walz

Usually very simple measures are used, especially for planning purposes, because they aremore demonstrative and more accessible to the public.

In studies a large number of numerical values are often generated, but it should be kept inmind that many landscape metrics are highly correlated.

Usually temporal dynamics are not considered, or not sufficiently considered. The ecologicalsignificance of a measured pattern is difficult to assess without an understanding of thehistorical variability of that pattern.

Vertical complexity is too little considered. However, it can be important for habitat mod-elling (e.g., for birds). Some developments are currently in progress (McGarigal and Cush-man,2005;Hoechstetter,2009;Hoechstetter et al., 2011), but further developments on eco-logical transitions and vertical structures appear necessary.

A comprehensive overall view on the state of research is lacking.

Often, one finds only very general statements on the relationship between landscape structureand biological diversity. Generally, there is still a deficit in converting findings about individualspecies to general knowledge about the relationship between landscape structure and biodiversity(Turner,2005, 331). The evaluation and prediction of species richness in complex landscapes re-mains a problem, because there is no simple scaling function of species diversity in a heterogeneousenvironment (Wagner and Edwards,2001, 121). At the species level, it is also difficult to postulatea general correlation between biodiversity and landscape parameters (Brotons and Rosell, 2001).Hence, for certain species, only land use is crucial; for others, the landscape structure in termsof relationships to neighbouring land uses or edge lengths of hedges, etc. are important (see also,e.g., Burel et al., 1998; Zebisch, 2002, 5). Moreover, the potential value of an area for conserva-

tion of biological diversity from the perspective of nature conservation does not depend on howmany species are present, but rather which ones (Wagner and Edwards,2001, 121). In addition,qualities of biodiversity which are recordable by landscape metrics are only a part of the reality.Biodiversity objectives should also be set on the basis of non-measurable qualities, such as naturalbeauty, wilderness and perceptibility of a landscape (Weinzierl,2004, 20).

Overall, it can be stated that the possibilities for the application of indices of landscape structurefor spatial planning and for environmental and nature conservation have not been fully exhausted.Since they are suitable as indicators of processes of land use development and environmentalstatus, such indices should more than ever find their way into spatial environment monitoring andinformation systems.

7 Acknowledgements

The author thanks Ms. Jurgens for her support in the extensive literature review, and Mr. Wendefor the review of the manuscript (both of the Leibniz Institute of Ecological Urban and RegionalDevelopment).



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http://dx.doi.org/10.1016/0169-2046(91)90037-Mhttp://dx.doi.org/10.1023/A:1011115921050http://dx.doi.org/10.1023/A:1011115921050http://dx.doi.org/10.1007/s10980-007-9108-4http://dx.doi.org/10.1007/s10980-007-9108-4http://dx.doi.org/10.1007/s10980-007-9108-4http://dx.doi.org/10.1007/s10980-006-9035-9http://dx.doi.org/10.1007/s10980-006-9035-9http://books.google.com/books?id=rZDHBrLfNJgChttp://books.google.com/books?id=rZDHBrLfNJgChttp://dx.doi.org/10.1016/S0169-5347(03)00011-9http://dx.doi.org/10.1016/S0169-5347(03)00011-9http://books.google.com/books?id=aPe2Uzva5NsChttp://www.livingreviews.org/lrlr-2011-3http://www.livingreviews.org/lrlr-2011-3http://books.google.com/books?id=aPe2Uzva5NsChttp://dx.doi.org/10.1016/S0169-5347(03)00011-9http://books.google.com/books?id=rZDHBrLfNJgChttp://dx.doi.org/10.1007/s10980-006-9035-9http://dx.doi.org/10.1007/s10980-007-9108-4http://dx.doi.org/10.1023/A:1011115921050http://dx.doi.org/10.1016/0169-2046(91)90037-M


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